Arches

Arches sits off Cano Island, a biological reserve off Costa Rica's Osa Peninsula on the Pacific coast, reached by boat from operators based in Uvita or Drake Bay after a crossing of some distance across open water. The site takes its name from the island's volcanic rock formations, which form swim-throughs and arch-like structures along the coastline, and here the terrain includes caverns and overhead passages. It's rated an advanced dive to a maximum depth of around 14 metres, with the overhead sections a key reason for that grading. Divers have also reported glassfish schooling through the passages alongside whitetip reef sharks, king angelfish, guineafowl puffers, and redlip parrotfish, with bluefin trevally, Cortez rainbow wrasse, giant damselfish, and both whitecheek and yellowfin surgeonfish also turning up around the rock formations.

Confirmed by our research team, reported by independent divers, or observed nearby via iNaturalist — each entry is labelled with its source.

• GlassfishGlassfishReported here · unconfirmed
• Redlip ParrotfishScarus rubroviolaceusReported here · unconfirmed
• Yellowfin SurgeonfishAcanthurus xanthopterusReported here · unconfirmed
• Guineafowl PufferArothron meleagrisReported here · unconfirmed
• King AngelfishHolacanthus passerReported here · unconfirmed
• Whitetip Reef SharkTriaenodon obesusReported here · unconfirmed
• Bluefin TrevallyCaranx melampygusReported here · unconfirmed
• Cortez Rainbow WrasseThalassoma lucasanumReported here · unconfirmed
• Giant DamselfishMicrospathodon dorsalisReported here · unconfirmed
• Whitecheek SurgeonfishAcanthurus nigricansReported here · unconfirmed